Why Does My Car Smell Like Onions?

Having a pleasant-smelling car interior transforms the driving experience into a comfy memory. Also, we love getting into our vehicles and being greeted by a fresh, inviting scent. But often, questions come like this: “why does my car smell like onions?”

Are you wondering why your car has that strange onion-like smell? It is pretty common to have unusual odors like onion in vehicles. Typically, the main reason for this peculiar smell is often leftover food. May be you have had meals or snacks recently sitting inside the car. So, the food remnants may cause an onion-like odor.

In this article, I will specifically explain the causes and the ways to deal with the odor. So, tackle this onion stench together!

Understanding Odors in Cars

While stepping into our vehicles, we expect a refreshing interior environment. But odors penetrate it and affect our driving experience and pleasure.

Factors Contributing to Car Odors

The car may smell like onions due to several external and internal factors.

External sources

External sources can be different environmental factors and nearby food remnants. Let me share an example. If you have parked your car near a restaurant, the food scent may quickly enter the vehicle.

Another example is pollution, industrial areas, or natural phenomena like wildfires, which are environmental factors that cause odors.

Internal sources

Internal sources for creating bad smells are usually related to activities and items inside the car. For example, food or beverage spills, improperly stored trash, and leftovers can create lingering odors.

Suppose you do not clean the upholstery, carpets, or other interior materials for long. In that case, you may smell irritating odors like an onion.

Impact of Onion-like Odors on Driving Experience

Unpleasant odors like onion in cars may have various negative impacts. They can be:

  • The driver and passengers may find riding the car uncomfortable and distracting.
  • Strong or offensive smells like onion may affect our concentration from driving correctly.
  • Everyone inside the car may feel reluctant to spend time which is resistance to long-distance traveling.
  • Onion-like odors may trigger allergies or respiratory issues in sensitive individuals.

Identifying the Onion-Like Smell

So far, you have been experiencing a peculiar onion-like smell in your car. Now, I will provide several indicators and distinguishing characteristics to identify the sources of it.

You can easily recognize the onion-like smell. Usually, it replicates the pungent, sulfurous aroma of freshly cut onions.

Identifying the sources to focus your efforts on the appropriate solutions is essential. For instance, if the source is food leftovers, you should concentrate on cleaning and removing them from nooks and crannies. Similarly, address the underlying moisture issue if the onion smells from mold or mildews.

Reports of Onion-Like Smell in Cars

In a thread on DetailngWorld, a member posted like this: “…it seems to have smelled of onions…” Thus, other people suggested cleaning the air conditioning to eliminate this smell.

A user of Reddit posted, “a weird smell coming from my SUV. The smell seemed to be like a burning garlic/onion smell.” He got suggestions to clean the hair and cat poop from the car and wash the whole vehicle with a pressure washer.

A member of 3Si.org forum reported the same thing, “After some hard pulls my car always begins to smell like onions.” Other members made food leftovers responsible for the bad odor.

An Uber driver was seeking help dealing with his vehicle’s onion odor. His passengers left some remnants of sandwich on the backseat. This was the possible reason for the aroma. So, the solution was to put a few dryer sheets overnight in the vehicle.

A Marcedes-Benz ML350 owner also experienced the same issue. But he shared how he got rid of it. He took his car to the dealer. Then, the dealer replaced the cabin filter, used particular fumigation, and suggested changing the sliding cover from the sunroof.

You may find many cases where people became frustrated to find out the reasons and solutions for onion-like odor. But here I am! I am describing everything related to this topic.

Possible Causes: Why Does My Car Smell Like Onions?

Some possible reasons why you are smelling the unpleasant onion-like scent inside the car are:

Spoiled or Rotting Food in the Car

Spoiled or rotting food or leftovers are common reasons for awkward onion odors inside the car.

You may have left some portions of meals or snacks unwillingly. To be precise, foods having onions, garlic, or strong-smelling spices are enough to leave persistent odors. Some foods can be onion rings and fast-food items with onion toppings. Even eating homemade dishes containing onion can also be responsible for the issue.

Some common hiding spots for leftovers are under the seats, between seat cushions, and in storage compartments. Also, there are reports of finding fragments inside the air conditioning vents.

Mold or Mildew Growth

If there is excess moisture or water leakage, it can lead to the development of mold or mildew colonies. These microorganisms release distinct musty or earthy odors. Hence, you may mistake them for an onion-like smell.

In a car, moisture may accumulate in carpets, floor mats, or the trunk. Water leaks, improper sealing, damp clothing, or even umbrellas brought into the car are possible reasons for that moisture.

Another common area for mold and mildew growth is the AC evaporator. The dark, damp environment within the system provides an optimal environment for their growth.

Additional Causes of Onion-Like Smell

Some other potential causes of onion-like odor are these:

You may have used certain chemicals or cleaning agents that emit odors like onions. Even some air fresheners or deodorizers may contain ingredients that produce almost the same scent. Again, excessive use of cleaning products may also leave residual odors resembling onions.

Sometimes mechanical problems within the engine or exhaust system may also be responsible. These problems can be related to fuel leaks, oil leaks, or the catalytic converter. Therefore, the fumes emitted from fuel or oil leaks may have a distinct scent.

If you carry chemicals with onion-like scents, you may experience that sitting inside the car. Environmental factors like high humidity or stagnant air can also be the reasons.

Solutions to Remove Onion-like Smell

In this section, I will discuss how to get free from your favorite car’s onion or other smells.

Dealing with Food-Related Odors

By following these below techniques, you can eliminate the food-related, onion-like odors and restore a fresh scent to your vehicle:


Inspect the car interior thoroughly for any visible food remnants, wrappers, or spills. Also, pay attention to commonly overlooked areas. These areas can be under the seats, between cushions, and in storage compartments.

Cleaning Methods

Now, use suitable cleaning agents and techniques based on the affected surfaces. You can use fabric cleaners to remove odor from fabric upholstery and carpets. Otherwise, use gentle all-purpose cleaners to clean hard surfaces like plastic or leather. You can use a soft brush or cloth to scrub away any stains, dried food, or liquid residues.

Always follow the usage instructions from the product you use for removing odors. You may test the item in a small, inconspicuous area before applying them more extensively.

Addressing Mold and Mildew Issues

If the onion-like odor happens due to mold and mildews, then you can follow these steps:


Inspect the vehicle properly for visible signs of mold or mildew. You may see discoloration, dark spots, or fuzzy growth on surfaces like upholstery, carpets, or the interior roof. Also, check out the places prone to moisture, like trunks, floor mats, or the AC.

Next, check for water leaks and ensure proper sealing of windows and doors. After that, fix any available issues with car’s ventilation system.

Cleaning Methods

Water and mild detergent solutions can remove mold from the affected surfaces. An alternative solution can be a mixture of vinegar and water.

If there is any visible mildew growth and stains, lightly scrub with a soft brush or cloth. Use specialized cleaners to eliminate any stubborn mold and mildew growth.

Drying Out the Car

Many experts suggest drying out the interior of your car correctly. It discourages mold and mildew growth. Open the windows or use fans to let the air circulate well. Likewise, you may park your vehicle in a well-ventilated area or under direct sunlight to aid the drying process.

You may use moisture-absorbing products to reduce humidity inside the car. These products are usually dehumidifiers or desiccant packs.

Other Solutions to Remove Onion-like Odors

Here are some other solutions to fight against the lingering scent:

Have you used a new air freshener or deodorizer in your car? You can prevent the onion scent by changing or removing the air freshener. After that, observe the interior to see if the smell dissipates over time.

Avoid strong-smelling cleaning products so the residues cannot create any onion-like odor. Again, if you find any fuel or oil leakage in the engine, address these leaks instantly.

Frequently Asked Questions

Question-1: Can Onion-Like Smells in Cars Be Harmful?

Answer: No, they are not harmful. But they can indicate underlying issues like food spoilage, mold growth, or engine problems. Consult a professional if you suspect any health hazards or if the smell persists despite your efforts to eliminate it.

Question-2: Can Air Fresheners Alone Solve the Problem?

Answer: Air fresheners can temporarily mask odors. They do not refer the underlying cause of the onion-like smell. So, you should identify and eliminate the source of the odor first. Then, use air fresheners as a complementary measure.

Question-3: Are There Any Natural Remedies Specifically for Onion Odors?

Answer: Natural remedies like baking soda, activated charcoal, or vinegar can absorb and neutralize odors, including onion smells.

Question-4: How Can I Prevent Future Occurrences of Food-Related Odors?

Answer: Avoid eating messy or strong-smelling foods while driving. Also, clean up any spills or food remnants quickly. Regularly vacuum and clean the interior to remove potential sources of odors.

Final Words

I hope you understand “why does my car smell like onions” well. The causes of this smell are possibly food-related, mold and mildew growth, and other technical issues in the car. You should identify them first and treat them accordingly.

Regular cleaning and maintenance are the best solutions to remove any foul odor from the vehicle. Also, follow the instructions I have discussed in this article. Have a great driving experience!

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